The present disclosure relates generally to medical devices and, more particularly, to non-invasive medical devices and methods used for determining physiological parameters.
This section is intended to introduce the reader to various aspects that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices may have been developed for monitoring many such characteristics of a patient. Such devices may provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become useful in treating patients.
Non-invasive medical devices may be particularly useful and desirable, as they generally provide immediate feedback and do not traumatize a patient. Generally, non-invasive sensors may transmit electromagnetic radiation, such as light, through a patient's tissue. The sensor may photoelectrically detect the absorption and scattering of the transmitted light in such tissue. The light passed through the tissue may be selected to be of one or more wavelengths that may be absorbed and scattered by particular tissue constituents, such as blood, for example. One or more physiological characteristics may then be calculated based upon the amount of light absorbed and/or scattered.
One non-invasive technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. In fact, the “pulse” in pulse oximetry refers to the time varying amount of arterial blood in the tissue during each cardiac cycle.
Pulse oximetry readings may measure the pulsatile, dynamic changes in amount and type of blood constituents in tissue. However, events other than the pulsing of arterial blood, such as noise received by the sensor, for example, may lead to modulation of the light path, direction, and the amount of light detected by the sensor, introducing error to the measurements. As such, various types of noise are primary causes of artifacts that may obscure determination of the blood constituent signal and make it difficult to obtain accurate measurements.